We had a previous thread on head retention likely being affected by the use of Jet Dry in the dishwasher (for bottles). So I will take an additional step and give all my bottles an additional idophor rinse prior to filling.

But the beer glasses go through the same dishwasher (no, I can't afford two DWs). So I figure it is best to rinse the glasses with tap water before pouring beer into them. I haven't done a good controlled experiment, but it almost seems like the wet glass negatively affects the head. Is that possible? Should the glasses be rinsed and then dried?

The common agreement among keggers in my club is that wetting bottles reduces foaming when filling them from a tap. They figure it has to do with water filling tiny scratches leaving fewer nucleation sites or something. I've never done any experiments myself, so I can't corroborate. Just passing along the received wisdom. But if it's true, it would support your observation that wet glasses show less head.

I'm still experiencing low head retention, despite rinsing the bottles in iodophor solution before bottling. I guess I'll wash and dry the beer glasses before using.

I generally put a half pound or so of wheat malt into almost all brews. Has not seemed to make a big difference. I guess I'll start adding a little carapils (carafoam) in the future. Any reason not to add some of both?

Wheat and/or carapils are band-aids for other problems in the process which are too numerous to mention here. Wheat obviously adds some protein, and carapils, some dextrins. Much has been written about head formation and retention over the years, and some quite recent articles have been featured in both BYO and Zymurgy.

I will say anecdotally, since I started brewing on my new system, I have step-mashed every single brew, with the steps varying with the grist and my desired end result. I have had generally outstanding head formation and retention in doing so. Other obvious contributors have been more hops in some beers, both bittering (IBU) and/or late or dry hopped. All of those things have helped. My higher-alcohol beers, not surprisingly, have suffered a bit in terms of retention, though they still do well in formation.

FWIW, I wash all my glassware in the dishwasher with a rinsing agent, and I haven't noticed a problem. That said, I have VERY soft water, and that may well be a factor in how the rinsing agent works.

I dislike carapils because I like dry beers, and I loathe the sweetness it adds. In an extremely narrow range of circumstances, it may have a place, but not in my brewery, and especially not in the interest of head formation or retention. But hey, that's just me.

For two or three beers, I've played with doing decoction mashes, not for the purpose of fixing poorly modified malt, but just to see if I can improve the malt flavor of the finished beer. In that light, I would mash-in at about 140 degrees and do a quick decoction or two to raise the mash to the mid 150's.

All of these brews poured with a large but very short lived head. Other beers, with very similar recipes but using a single infusion mashes did not have this problem.

I suspect the rest at 140 is destroying some important head-retention proteins.

Paul and Graham's posts seem a bit contradictory. Graham does step mashes on his new system and reports excellent head formation/retention. Paul does decoction mash (a variant of step mashing) and reports reduced head retention.

Proteins are important for head, right? And a step mash with a protein rest seems like it is going to "destroy" some of those. I'm inclined to agree with Paul and guess that there are other factors with Graham's new system that are giving him good head.

I withheld comment on Paul's post, but since you brought it up, Tex...

The vast majority of proteolytic activity occurs during malting. The so-called "protein rest" is of questionable efficacy with modern fully-modified malts for several reasons, but the most prominent is that most of the protease enzymes (there are at least eight separate ones that I know of) are very sensitive to heat, and they are largely denatured during kilning. In all but the very palest malts, a protein rest is pointless, IMHO.

Now, there are glucanase enzymes that survive in various malts. That is another story.

Bottom line, a rest at 140°F is (1) well above what the protease enzymes can endure, and (2) in anything darker than the palest pils, they're pretty much dead anyway. So, with respect to Paul, a rest at 140°F is not likely to destroy much other than the carbon bonds of the amylose and amylopectin molecules as beta-amylase performs its short-lived purpose in life. (It dies quickly, too, even within its optimal temperature range.)

Admittedly, my empirical observation was based on an extremely small sample size (three brew sessions). I did read somewhere that a rest in the temp range of 120-140 degrees may have an adverse effect on head retention for well modified malt (I think it was an article on the BeerSmith blog site).

I should have known I was going out on a limb in questioning Graham on a subject like this.

I am sure this has been addressed before, but could you please reiterate the benefit of the 140 deg. rest (for how long?) and why you want to "destroy the carbon bonds of the amylose and amylopectin molecules as beta-amylase performs its short-lived purpose in life." What is it's purpose in life? How could this affect head formation/retention?

For my purposes, all I wanted to do was see if boiling a portion of the mash had any effect on the malt flavor of the finished beer. I infused to 140 degrees so I could do just one decoction to get up to the target rest temp I wanted without too much work.

I don't think any traditional decoctions have a rest in the 140 degree area, but I am not well studied in this area.

I am sure this has been addressed before, but could you please reiterate the benefit of the 140 deg. rest (for how long?) and why you want to "destroy the carbon bonds of the amylose and amylopectin molecules as beta-amylase performs its short-lived purpose in life." What is it's purpose in life? How could this affect head formation/retention?

Tex, you have two primary enzymes that break down starch into fermentable sugars, beta-amylase, which works best in the 140°F range, and alpha-amylase, which works best in the 158°F range. Most simple brewing books recommend a single-temperature rest at 152°F, as this doesn't immediately denature the beta-amylase, and it is still warm enough for alpha-amylase to work. While an effective compromise, this is, like most simple advise, a great oversimplification.

The proteolytic enzymes described above, at least some of them, are not completely dead. Then there are beta-glucanase enzymes. Then there is beta-amylase itself, which, again, is quite fragile. All of these are active for some period if you choose to mash in at 140°F for an all barley malt mash. Most of what I have read, however, is that even under optimal temperature and pH conditions, beta-amylase has a half-life of less than half an hour. Alpha-amylase, on the other hand, is very resiliant, resistant to extremes of either temperature or pH.

So, let's review. We have a lot of very fragile enzymes that really, REALLY like the lower tiers of the 100°F range. Then we have alpha-amylase, which cares not so much about temperature with regard to denaturing, but performs best in the 150°F+. Then there is the oft-overlooked limit-dextrinase, which also performs best in the range of the alpha-amylase.

To specifically answer your question, the benefit of a 140°F rest with an all barley-malt grist is that it will allow not only maximum beta-amylase activity, but also secondarily, some beta-glucanase activity and also, as an extreme tertiary element, some really miniscule proteolytic activity, not worth mentioning except in the context of a conversation in which somebody brought it up.

Time? Longer than 40 minutes and beta-amylase is denatured to such a degree that further time at this temp is worthless, in my understanding. I would only use a rest this long in a situation in which I wanted an extremely dry beer, like a Tripel.

Now, the reality of all of this is that there is an awful lot of overlap in all these enzymes. The book says beta-amylase, for example, is rapidly denatured about 149°F. Is it INSTANTLY denatured? No, it is not. Same for all of the lower-temperature enzymes that are important for head formation/retention. That said, a beginning rest at, say, 140°F, gives them an opportunity to work better than an initial (or single) rest at 152°F.

Very good explanation, Graham. What is beta amaylase acting on? "amylose and amylopectin molecules"? Why do you want those converted? You mention making the beer drier. What if you don't want a drier beer? And relevant to this thread, what effect does it have on head formation/retention?

Amylose and amylopectin are the two forms of starch. Amylose is a straight chain of glucose molecules and amylopectin, a branched structure. That is what all three of the amylolytic enzymes are working on, and for good reason - yeast can't do anything with those enormous starch molecules, they only can ferment 1, 2, and 3 carbon-ring sugars.

If you don't want a drier beer, you can certainly mash warmer so that more residual dextrins remain in the beer, but dextrins do not provide much in the way of sweetness that the human palate can detect. I prefer a mash regimen that converts my base malts to the maximum extent possible, and any residual sweetness desired is provided by specialty malts that are largely unfermentable anyhow, no matter what the mashing regimen. An added benefit of using crystal malts is the unfermentable dextrins they provide that are foam-positive.

("Wait just a damn minute here! You just said dextrins from base malts aren't that sweet and then said dextrins from crystal malts are sweet! WTF, man? I don't think you know what the hell you are talking about.")

Kilning. Raw onions don't taste sweet, but when you cook them, they become sweet.

Dextrins are foam-positive. Carapils has dextrins. "I dislike carapils because I like dry beers, and I loathe the sweetness it adds." Is carapils sweet like crystal malts? But mainly, how are you getting good head formation/retention? You still haven't answered my question about the beta amaylase effect on head.

I don't think beta-amylase has any direct impact on head formation. I do think that a beta rest at about 140°F perhaps allows a brief period of activity for the remaining proteolytic enzymes and for beta-glucanase to work before they are denatured, as they will be fairly rapidly at that temperature. More to the point, however, is that they would be more rapidly denatured at 152°F or 156°F, or whatever higher temperature compromise you chose.

The "destruction of proteins" is not an accurate description of what is happening in that arena. Proteins are similar to starches, in that they are long chains of simpler molecules, but in the case of proteins, they are amino acids instead of simple sugars (nitrogen being the primary game-changer there). Proteolytic enzymes work like amylolytic enzymes, in that some nibble and some chop more haphazardly. Bottom line, though, is that a very complex protein molecule doesn't just explode and disappear. It may be broken into smaller parts, from complex protein to polypeptide to peptide to amino acid, but it doesn't just go away. It is those polypeptides that I understand to be the foam-positive proteins, so you as a brewer don't want proteolytic conversion to continue past that point if you are working solely in the interest of foam formation and retention.